[openmp] fix a compile error on musl-libc

[zlei]

Summary

Function strerror_r() has different signatures in different implementations of libc: glibc's version returns a char*, while BSDs and musl return a int. libomp unconditionally assumes glibc on Linux and thus fails to compile against musl-libc. This patch addresses this issue.

[mgorny]

runtime/src/kmp_i18n.c

812 ↗

(On Diff #72983)

Hmm, wouldn't it be reasonable to just check for GLIBC? I think non-Linux (Hurd?) glibc would have the same signature, wouldn't it?

[zlei]

runtime/src/kmp_i18n.c

812 ↗

(On Diff #72983)

Agree. Although I don't know if anyone is really building libomp on those niche platforms.

[jlpeyton]

_GNU_SOURCE has to be defined for the char* version to be used (which we do by sending in -D_GNU_SOURCE during compilation). So have the #if be

#if defined(__GLIBC__) && defined(_GNU_SOURCE)

[AndreyChurbanov]

LGTM

[jlpeyton]

LGTM too.

[mgorny]

@zlei, I presume you still don't have commit access, so I'll commit it for you, and backport it on Gentoo end. Thanks for working on this.

openmp/trunk/runtime/src/kmp_i18n.c

#else // Non-Windows* OS: Linux* OS or OS X*
 
         /*
             There are 2 incompatible versions of strerror_r:
 
                 char * strerror_r( int, char *, size_t );  // GNU version
                 int    strerror_r( int, char *, size_t );  // XSI version
         */
 
-        #if KMP_OS_LINUX
+        #if defined(__GLIBC__) && defined(_GNU_SOURCE)
 
             // GNU version of strerror_r.
 
             char   buffer[ 2048 ];
             char * const err_msg = strerror_r( err, buffer, sizeof( buffer ) );
                 // Do not eliminate this assignment to temporary variable, otherwise compiler would
                 // not issue warning if strerror_r() returns `int' instead of expected `char *'.
             message = __kmp_str_format( "%s", err_msg );